Prenatal stress doesn’t end at birth: The children of mothers who experience stress during pregnancy show long-term side effects, including cognitive and language delays and increased rates of attention and behavior problems. Annie Murphy Paul, author of Origins: How the Nine Months Before Birth Shape the Rest of Our Lives, describes one surprising study.

On January 6, 1998, a freezing rain began to fall over a wide swath of Canada, the start of what was to become the worst natural disaster in the country’s history. As temperatures plunged and the rain turned to ice, millions of people lost heat and electricity. Soon grocery stores ran out of bread; gas stations emptied their tanks; hardware stores sold out of generators and oil lamps. Banks and pharmacies served their customers by flashlight or candlelight, and hospital emergency rooms filled with people with bones broken from slipping on the ice.

One of the people caught in the ice storm was Suzanne King, an associate professor of psychiatry at McGill University in Montreal. “The ice froze on everything — on the streets, the sidewalks, even on the high tension lines, which toppled huge transmission towers like dominoes,” King tells me. When she tried to clear the rain from her car windows, her windshield wiper snapped in two. King’s husband was out of town on a business trip, so she was alone in caring for her two children, aged six and four. When the electricity in her house went out, she moved the family to her mother-in-law’s, then to her younger child’s preschool, as each place in turn lost power.

“We think we’re so civilized and then we plummet right down to the bottom, to matters of survival,” King says. “I was driving around town looking to buy water to drink, to buy fuel to cook with. It was all about the basics — food, water, shelter, staying warm. The hardest thing was not knowing how long it was going to go on.” Finally, the rain stopped and the cold relented — but that wasn’t the end of it for King. “A few days after things had returned to normal, I went to donate blood, since the hospitals were running low,” she recalls. “The nurse took my blood pressure, and it was sky high. That’s weird, I thought — and then I realized that my body was still stressed out from our experience during the ice storm. I immediately wondered: What is this doing to pregnant women and their fetuses?”

King’s turn of thought was prompted by her psychiatric research, which focuses on risk factors for schizophrenia. She knew that maternal stress during pregnancy has been implicated in the development of this mental illness, and she saw in the ice storm an opportunity to observe the effects of such adversity in real time, following prenatally stressed offspring from birth onward. Within months King had initiated Project Ice Storm, sending out a survey that posed questions like: How many days were you without electricity? How often were you required to change residence during the ice storm? Did your family stay together for the duration of the ice storm? Was anyone close to you injured?

King and her colleagues began following more than 150 women who had been pregnant during the storm, administering questionnaires to the mothers and tests to their children at periodic intervals. Their earliest results showed that the more stressful events pregnant women encountered during the disaster, the lower were their babies’ birth weights. Evaluations performed when the offspring were two years old revealed an association between prenatal stress and cognitive and language skills: the more severe the stressful events experienced during pregnancy, the poorer were their toddlers’ abilities. A third round of tests performed when the children were five and a half showed continued cognitive and language delays, as well as increased rates of attention and behavior problems, among children whose mothers endured high levels of hardship during the ice storm.

Now ten years old, the children of women who encountered great adversity during the ice storm have displayed differences at every stage from kids whose mothers had an easier time. To be sure, these differences are subtle — “variations in normal,” as King puts it. Most of the high-stress children are doing well in school, and most score above average on IQ tests, albeit ten to twenty points lower than the low-stress control children. But the differences are present and persistent, a result that King finds surprising and dismaying. “The impact of ice storm stress on the offspring is greater than I thought it would be,” she tells me. “I was surprised to find effects on the kids when they were two years old. And I thought for sure by the time they were five, or eight, the prenatal effects would have washed out and the postnatal environment would have taken over. But that’s not what we’ve found.” After following these children for more than a decade, King says, “I have a lot more respect for the impressionability of the fetus. Historically, people knew that it was a good idea to take special care of pregnant women. But in modern times, we’ve forgotten that.” Especially in crisis situations, she says, “we need to see pregnant women and their fetuses as high priority.”

ABOUT THE AUTHOR
What makes us the way we are? Some say it’s the genes we inherit at conception. Others are sure it’s the environment we experience in childhood. But could it be that many of our individual characteristics — our health, our intelligence, our temperaments — are influenced by the conditions we encountered before birth? In her new book Origins: How the Nine Months Before Birth Shape the Rest of Our Lives, Annie Murphy Paul, a journalist whose writing has appeared in The New York Times Magazine, Slate, Discover, and The Best American Science Writing, among other publications, explores the rich history of ideas about how we’re shaped before birth. You can follow her on Twitter @anniemurphypaul.